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#pragma once

#include "findcursorusr.h"

#include <clang/AST/ASTContext.h>
#include <clang/AST/RecursiveASTVisitor.h>
#include <clang/Basic/SourceLocation.h>
#include <clang/Index/USRGeneration.h>
#include <llvm/ADT/SmallVector.h>

#include <vector>

namespace ClangBackEnd {

class FindLocationsOfUSRsASTVisitor : public clang::RecursiveASTVisitor<FindLocationsOfUSRsASTVisitor>
{
public:
    explicit FindLocationsOfUSRsASTVisitor(const std::vector<USRName> &unifiedSymbolResolutions)
        : unifiedSymbolResolutions(unifiedSymbolResolutions)
    {
    }

    bool VisitNamedDecl(const clang::NamedDecl *declaration) {
        auto declarationUSR = USROfDeclaration(declaration);

        if (containsUSR(declarationUSR))
            foundLocations.push_back(declaration->getLocation());

        return true;
    }

    bool VisitDeclRefExpr(const clang::DeclRefExpr *expression) {
        const auto *declaration = expression->getFoundDecl();

        iterateNestedNameSpecifierLocation(expression->getQualifierLoc());
        auto declarationUSR = USROfDeclaration(declaration);

        if (containsUSR(declarationUSR))
            foundLocations.push_back(expression->getLocation());

        return true;
    }

    bool VisitMemberExpr(const clang::MemberExpr *expression) {
        const auto *declaration = expression->getFoundDecl().getDecl();
        auto declarationUSR = USROfDeclaration(declaration);

        if (containsUSR(declarationUSR))
            foundLocations.push_back(expression->getMemberLoc());

        return true;
    }

    bool shouldVisitTemplateInstantiations() const
    {
        return true;
    }

    std::vector<clang::SourceLocation> takeFoundLocations() const {
        return std::move(foundLocations);
    }

private:
    void iterateNestedNameSpecifierLocation(clang::NestedNameSpecifierLoc nameLocation) {
        while (nameLocation) {
            const auto *declaration = nameLocation.getNestedNameSpecifier()->getAsNamespace();
            if (declaration && containsUSR(USROfDeclaration(declaration)))
                foundLocations.push_back(nameLocation.getLocalBeginLoc());

            nameLocation = nameLocation.getPrefix();
        }
    }

    bool containsUSR(const USRName &unifiedSymbolResolution)
    {
        auto found = std::find(unifiedSymbolResolutions.cbegin(),
                               unifiedSymbolResolutions.cend(),
                               unifiedSymbolResolution);

        return found != unifiedSymbolResolutions.cend();
    }

private:

    // All the locations of the USR were found.
    const std::vector<USRName> unifiedSymbolResolutions;
    std::vector<clang::SourceLocation> foundLocations;
};

inline
std::vector<clang::SourceLocation> takeLocationsOfUSRs(std::vector<USRName> &unifiedSymbolResolutions,
                                                     clang::Decl *declartation)
{
  FindLocationsOfUSRsASTVisitor visitor(unifiedSymbolResolutions);

  visitor.TraverseDecl(declartation);

  return visitor.takeFoundLocations();
}

} // namespace ClangBackend
